Field of the Invention
The invention relates to a capillary device for separation and analysis, a microfluidic chip for separation and analysis, an analysis method for proteins or peptides, an electrophoresis instrument, and a microfluidic chip electrophoresis instrument for separation and analysis.
Description of the Related Art
A protein even being originated from a single gene often exists in multiple molecular forms produced by post translational modification, such as phosphorylation, glycosylation, etc. The distribution pattern of these molecular forms is related to the regulation of the function of the protein in cells and individuals. In a view from the other side, the distribution pattern can be considered to reflect the conditions of the cells and individuals enabling to provide valuable information about the condition of the organism. As a promising method for the analysis of the pattern of the molecular forms produced by post translational modification, capillary isoelectric focusing should be noticed having high-separation ability and completing separation in a short time.
There are, however, two main issues, when a biological sample such as serum and the like is analyzed by capillary isoelectric focusing.
One issue is that highly abundant proteins such as albumin mask the target protein present at low concentration, and make it difficult to detect the target protein. Besides, highly abundant proteins precipitate during separation process and cause generation of noise at the step of detection.
Another issue is that the salts present in the sample elongate the time required for focusing during isoelectric focusing and change a separation pattern.
For these issues, in Non-patent Reference 1, as a method of analysis using a protein analysis instrument, a method to link solid-phase extraction and isoelectric focusing is proposed.
Up to now, devices aimed at the online connection of solid-phase extraction and zone electrophoresis have been proposed.
For example, in Patent Reference 1, a structure of capillary electrophoresis instrument and an online sample concentration adsorbents unified with a capillary for zone electrophoresis to be used in the above instrument were disclosed.
In Patent Reference 2, a structure of an online adsorption column that is aimed to accomplish concentration of dilute sample in capillary zone electrophoresis was proposed.
In Patent Reference 3, in capillary zone electrophoresis, online coupling with the adsorbent concentrating a low concentration sample was proposed.
In Non-patent Reference 2, using combination of a capillary for solid-phase extraction, in which octadecyl group is bound on its inner wall, with a capillary for zone electrophoresis, it is demonstrated that detection sensitivity can be improved by online separation of concentrated sample in the octadecyl-bound moiety.
Besides, in Non-patent References 3˜6, the online coupling of solid-phase extraction and capillary zone electrophoresis was examined.
On the other hand, in Non-patent Reference 7˜8, a microfluidic chip aiming at integration of solid-phase extraction and isoelectric focusing by means of manifold channels was disclosed. To be specific, the microfluidic microchip described in the non-patent Reference 7˜8 was designed to achieve connection of the channel for isoelectric focusing to electrodes by filling the manifold channels with electrode solutions after eluting a target protein from the solid phase extraction adsorbent into the channel for isoelectric focusing.